Metal halide lamp

Abstract

In a metal halide lamp including a luminous sealed tube which is equipped with a pair of discharge electrodes and has an inonizable inert gas and mercury sealed therein, the luminous sealed tube further includes, in addition to tin halide (exclusive of tin fluoride), calcium halide (exclusive of calcium fluoride) or strontium halide (exclusive of strontium fluoride) or their mixture. The metal halide lamp shows a high color rendering property.

What we claim is: 
     
       1. A metal halide lamp including a luminous sealed tube containing a pair of discharge electrodes and having an ionizable inert gas, mercury and halides sealed therein, said halides comprising at least one kind selected from the group consisting of tin chloride, tin bromide and tin iodide, and at least one kind selected from the group consisting of calcium chloride, calcium bromide, calcium iodide, strontium chloride, strontium bromide, and strontium iodide. 
     
     
       2. A metal halide lamp according to claim 1, in which said halides comprise at least one kind of tin halide selected from the group consisting of tin chloride, tin bromide and tin iodide and at least one kind of calcium halide selected from the group consisting of calcium chloride, calcium bromide and calcium iodide, and an amount of said tin halide is 0.1 to 5.0 mg per ml of an inner volume of said tube and an amount of said calcium halide is 0.005 to 3.0 mg per ml of the inner volume of said tube. 
     
     
       3. A metal halide lamp according to claim 1, in which said halides comprises at least one kind of tin halide selected from the group consisting of tin chloride, tin bromide and tin iodide and at least one kind of strontium halide selected from the group consisting of strontium chloride, strontium bromide and strontium iodide, and an amount of said tin halide is 0.1 to 5.0 mg per ml of the inner volume of said tube and an amount of said strontium halide is 0.01 to 3.0 mg per ml of the inner volume of the tube. 
     
     
       4. A metal halide lamp according to claim 1, in which said halides comprise at least one kind of tin halide selected from the group consisting of tin chloride, tin bromide and tin iodide, at least one kind of calcium halide selected from the group consisting of calcium chloride, calcium bromide and calcium iodide, and at least one kind of strontium halide selected from the group consisting of strontium chloride, strontium bromide and strontium iodide, and an amount of said tin halide is 0.1 to 5.0 mg per ml of the inner volume of said tube, an amount of said calcium halide is 0.01 to 3.0 mg per ml of the inner volume of said tube and an amount of said strontium halide is 0.01 to 3.0 mg per ml of the inner volume of said tube.